King DeeDee
At the begining, grab the two bubbles. If you don't currently have an ability, use the beam ability and save the ice for later. Enter the room and start the fight. At the start of the fight, run up to him and use beam until he starts coming closer. Fly over his head and do the same thing on the other side. Repeat hitting him until he is defeated. Grab the chest and continue to the next world.
Giant Mole
Grab the three bubbles and see what's in the ? Bubble. If it's something not very good, use the fire ability and start the fight. When the mole sticks his head out of the hole, use fire on him until he starts throwing objects. Dodge these until he goes underground agian. If he is in one of the backround holes, stand in the very middle until the shadow over you changes from small to big. When this happens, run to the left side as fast as you can. Just use fire until he gets up and goes back in the hole. Keep on doing these things until he is defeated. Grab the chest and continue to the next world.
Cyclopes Cloud
Grab the two bubbles and use the tornado ability. Start the fight and wait until the Squeak Squad Boss is gone. Just keep on using the tornado ability on him until his health is gone. After that, his health will come back and he will destroy the cloud that you were standing on. Wait until he creates another cloud for you to stand on. CAREFULLY attack him with the tornado ability agian until his health is gone agian. This time you have beaten him for real. Grab the chest and continue to the next world.
Robotic Turtle
Grab the two bubbles and use the tornado ability. Start the fight and wait until the Squeak Squad Boss is gone. The Robotic Turtle will appear and start making things fall on you. Just keep on using tornado over and over agian until he is defeated. Grab the chest and continue to the next world.
Fire Owl
Grab the two bubbles and use the hi-jump ability. Before you start the fight, turn the volume on your DS up. It is easier to tell what he's about to do if you can hear him. When you start, stand on the right patch of land until he appears. He should make a squeaky kind of noise. Remember this sound, because it is important. Use the hi-jump on him repeatedly until he makes another squeak. Stand on the middle tile and he should dive towards you. Dodge it and he will hit the ground. This will take off a good amount of his health. Repeat this until he is defeated. Grab the chest and continue to the next world.
Squeak Squad Boss
Get ready, because this is, by far, the hardest boss in this game so far. Grab the two bubbles and use the tornado ability. Start the battle and wait while his health goes up. IT IS IMPORTANT that if you have the tornado scroll, start on the ground so you have an ice tornado. This increases the damage to twice the amount. He will use four different abilities at random. The first ability is teleport. He does this the most often, and he can teleport anywhere on screen. The second is bomb. He does this pretty rarely, and it is very easy to dodge. The third is the Triple Star Rod. This is his second most often attack. It's very hard to dodge, so watch your guard. And the fourth is ice. It's pretty often, so watch out! After you beat him, grab the chest and move on.